How long can a leech stay without food?

Two years! Without a single drop of blood! There are three jaws in leech’s throat – the so called chipped plates. By making a skin cut with the help of these plates a leech can suck the blood. Meanwhile its salivary glands produce such an element as herudin, which prevents blood from setting. That’s why blood keeps floating without any obstacles straight into the stomach, filled up with capacious growths keeping bigger amount of blood inside. And really, such a relatively small creature (with a length that almost never exceeds 12 cm) can drink around 50 grams of blood at the time. Once a leech sucks enough blood it becomes 3-4 times thicker and just falls off the body by itself. Special bacteria residing in its bowel digests blood in truly extraordinary way so that it doesn’t get rotten and remains fresh for long period of time. That’s why leeches usually feed once in half a year and like it was mentioned before can survive without food for another two years.

fresh wate rleech

fresh wate rleech

Because of this truly unique ability some of the scientists see a grand future of leeches: they can easily become experimental animals used for flying rockets for space missions.

When a leech sucks blood from a live vertebrate creature, in order not to fall off the victim it gets sticked to the skin with the help of the two suckers – one located in front and the other one in the back. A small wound remains on the skin, and you can notice blood still leaking out of it, as herudin stays inside the wound once it was bitten and doesn’t allow the blood to set. One more interesting fact – leeches even have eyes! For example, a medicinal leech has five pairs of eyes – all located on the side of the “head”.


There are different kinds of leeches. In general, there are about 400 species. Most of them have a flat shape and can be of a black, green or brown color. They can vary in size as well. There are such tiny species, that stay almost invisible, while the others reach 1 meter in length. Such species of leeches usually reside in the sea, and the leeches of small and medium sizes, up to 20 centimeters are usually met in the fresh waters, like ponds, lakes and rivers.

As a rule, small fresh water leeches are not dangerous for people.

Besides blood sucking leeches there are also predator ones: this kind attacks and kills worms, maggots and other small creatures whom they can handle. Most of the leeches prefer to reside in the fresh waters of standing ponds, drains and slow current rivers. Some of the less salty seas like Azov and Caspian one also serve as a home to some leeches. However there are no leeches found in the Black Sea.

leech sucks blood

leech sucks blood


Subtropics and tropics host leeches who totally abandoned water – the land-based ones. Some of them are a torture for many animals, even so big as elephants. In order to clean the body from the sticked leeches, an elephant takes a wooden stick and scratches the body.

Back in ancient times, leeches used to be the most popular medical remedy. Doctors used to prescribe leeches to suck out the bad blood from the body of sick person. Though in reality there is no such notion as bad or good blood, but if you take out a small part of blood from a sick person, the body starts an active production of fresh , rich in hemoglobin blood. This was the main purpose of the leeches. Even nowadays there are some cases when leeches can be used in treating diseases. Moreover herudin is actively used in medicine as well.


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